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Follicle Stimulating Hormone (FSH), Serum Follicle Stimulating Hormone (FSH) secretion by the pituitary is under dual control by the hypothalamus and the gonads. The hypothalamus produces GnRH, which maintains basal FSH secretion. The testes and ovary produce inhibin, a hormone that inhibits FSH secretion. In men, FSH stimulates Sertoli cells to undergo spermatogenesis.In women, FSH stimulates ovarian follicle maturation and, together with LH, stimulates estrogen secretion and ovulation. Measurement of serum FSH is useful in the work up of patients with delayed or precocious puberty, infertility, and pituitary disorders. FSH levels are measured in infertility to distinguish primary failure of the ovary or testes from pituitary hypofunction. FSH levels are decreased in patients with pituitary failure and increased in patients with ovarian disease. Menopause is clinically defined as the absence of menses for 12 months. Natural menopause occurs at an average age of 51 years. Approximately 1% of women become postmenopausal before 40 years of age and 5% become postmenopausal after 55 years of age. During several years before menopause, serum levels of FSH increase and ovarian follicles abnormally mature. As a result estrogen and progesterone levels become erratic. Serum FSH levels >40 IU/L document with certainty that ovarian function has ceased. FSH levels are elevated in men with primary testicular failure, castration, and Klinefelter’s syndrome. FSH levels are elevated in women with menopause, ovariectomy, ovarian agenesis, and Turner’s syndrome. FSH secreting pituitary tumors are rare and do not produce a distinct endocrine disorder. FSH levels are decreased in men with hypopituitarism, hypophysectomy, adrenal tumors, and testosterone medications. In women, decreased FSH levels are seen in; hypopituitarism, hypophysectomy, adrenal or ovarian tumors, polycystic ovaries, Sheehan’s Syndrome, menstrual disorders, oral contraceptives, and estrogen therapy. Reference range is:

Gender

Reference Range mIU/mL

Male

<16

Female

Follicular

1 - 8

Ovulation

4 - 25

Luteal

1 - 5

Postmenopausal

40 - 100

Follicle stimulating hormone and luteinizing hormone Both FSH and LH are regulated by the hypothalamic release of gonadotropin-releasing hormone. In males, both hormones are inhibited via negative feedback by testosterone. In females, both hormones are inhibited via negative feedback by estrogen and progesterone. Levels of these hormones show pulse variation; this is especially true of LH and for this reason, 24-hour urine levels are preferred by some clinicans over plasma measurements. FSH and LH are performed when a person exhibits abnormal reproductive function. In women such conditions as precocious puberty, polycystic ovaries, failure to ovulate, dysmenorrhea, and the onset of menopause are the primary reasons for measuring these hormones. In males, these hormones are measured along with testosterone to diagnose and differentiate the cause of gonadal failure. Levels of FSH and LH are somewhat constant prior to puberty. At puberty, both hormone levels increase significantly. In women the levels of both hormones varies with the phase of the menstrual cycle. Both FSH and LH peak in the midcycle just prior to ovulation. Prior to this peak levels are somewhat higher than they are after ovulation. The midcycle peak has been used to identify the best opportunity to conceive. A urine LH detection kit is available for use at home. This test is sometimes called an "ovulation test" and is similar to a home pregnancy test. A sample of the woman's first morning urine is tested with the materials provided in the kit. These home tests may be used by women who want to become pregnant. By monitoring levels of LH and watching for the surge signaling ovulation, a couple can time sexual intercourse to increase the chance that the egg will be fertilized. Follicle-stimulating hormone (FSH), one of two gonadotropic hormones (i.e., hormones concerned with the regulation of the activity of the gonads, or sex glands) produced by the pituitary gland. FSH, a glycoprotein operating in conjunction with luteinizing hormone (LH), stimulates development of the graafian follicle, a small, egg-containing vesicle in the ovary of the female mammal; in the male, it promotes the development of the tubules of the testes and the differentiation of sperm. Though in the male the presence of FSH is necessary for the maturation of spermatozoa, additional FSH may not be required for months because testosterone can maintain this activity. In the female, however, there is a rhythmic, or cyclical, increase and decrease of FSH, which is essential for monthly ovulation. LH and FSH are measured mainly by enzyme or chemiluminescent immunoassays. In males, testosterone RIA is used along with FSH and LH to differentiate the cause of gonadal failure. A low testosterone with low LH or FSH points to a hypothalmic-pituitary cause. A low testosterone with an increased LH and/or FSH indicates primary testicular failure. In females, LH and FSH are measured along with estrogen, progesterone, and prolactin to investigate the cause of abnormal gonadal function. In menopause, the midcycle peaks for both LH and FSH are usually higher than in normal menstruating females. Prior to menopause, the LH peak is greater in magnitude than FSH. However, in menopause, this pattern reverses. In females, low plasma estrogen and progesterone seen with elevated serum or urinary levels of LH and FSH signal primary ovarian failure. Conversely, low estrogen and progesterone in association with low levels of LH and FSH indicate pituitary (secondary) hypogonadism. Prolactin levels should also be performed when evaluating hypogonadism in females. High plasma prolactin caused by pituitary adenoma causes inhibition of LH and FSH by negative feedback. Therefore, prolactinoma may be responsible for ovarian failure.

What Is FSH? Follicle-stimulating hormone (FSH) is a hormone that plays a role in the regulation of sexual reproduction in both men and women. In addition to being involved in sexual reproduction, it also plays a role in the onset of puberty and menopause. Tests for levels of this hormone in the body are sometimes used to explore causes of infertility, and the diagnose the onset of menopause or puberty. FSH is also used in infertility treatments, in the form of injectable medications. This hormone is in a class of compounds generated by the body known as gonadotropins. Gonadotropins are proteins, and they are produced by the section of the pituitary gland that is involved in the production of endocrine hormones. In women, FSH tells the follicles in the ovary to mature so that the woman can ovulate, releasing an egg into the uterus. Some doctors liken it to a gas pedal that is pushed by the anterior pituitary gland to start the engines of the ovarian follicles. In men, FSH is involved in sperm production. As a general rule, FSH levels are low in childhood, because children need neither sperm nor eggs. At puberty, levels begin to increase, as the body prepares for sexual reproduction. In women, FSH levels are highest around the time of ovulation, and they will continue to rise into menopause, as more and more of the hormone is needed with each ovulation to stimulate the follicles into maturity, since fewer eggs are left. When unusually high FSH levels are documented, it can be a sign that a woman is lacking viable eggs, which could contribute to fertility problems. High FSH in men is a sign that there is a problem with sperm production, and in both sexes, high levels have been linked with some other medical conditions as well. Extremely low FSH levels are linked with a decrease in the function of the gonads. When women undergo fertility treatment because they are unable to conceive on their own, FSH injections are used to stimulate the follicles artificially. Using this hormone ensures that the process is more controlled, and allows medical professionals to increase levels in the hopes of getting at least one viable egg so that they can sweep in at the perfect moment to retrieve eggs. However, as many infertile women are aware, FSH injections are only one stage in a very long process, and they do not always work; the course of injections may have to be repeated several times before success is achieved.

What Is the Role of FSH? The follicle stimulating hormone, (FSH) has several duties in both men and women, mostly related to the reproductive system. In women, it promotes egg production, along with the release of estrodiol hormone during the initial part of the monthly reproductive cycle. In men, it enables sperm production. In both cases, the hormone might be one of the prime things considered when looking at some types of reproductive disorders. In both males and females, the hormone is secreted by the anterior pituitary gland, but then goes on to do different things. In females, FSH typically peaks at certain times associated with the middle of the menstrual cycle. In this case, the increased hormone results in ovulation, or release of the egg from the ovary, where it then goes into the fallopian tube. Without this specific hormone, the cycle will not take place, and a pregnancy cannot occur. Thus, understanding the role of FSH is very important for the proper functioning of many birth control products. Many of those products work by inhibiting the release of large amounts of the hormone so that an egg is never released from the ovaries. As long as the hormone remains regulated, without the spikes, the ovulation never takes place. That is also the reason why many hormone-based birth control methods also seem to stop a woman's monthly cycle. In males, FSH is responsible for a couple of different things relating to reproduction. First, it helps stimulate the growth of the testicles. Second, it aids in the production of Sertoli cells, which help to sustain mature sperm cells. In order for the hormone to be effective in these areas, it must also work with the luteinizing hormone. Whether in men or women, FSH can sometimes be influenced by other hormones, leading to undesirable situations such as the inability to conceive. In such cases, doctors may advise some type of hormone therapy to help suppress, or alternatively to stimulate, the follicle stimulating hormone. Those who feel they may have a problem in this area should go to a doctor specializing in reproduction. FSH could also be responsible one of the things responsible for balding in men. Low levels of the hormone, along with low levels of other hormones, were associated with hair loss in men. A test can determine if a male or female has low levels of the hormone. Typically, the treatments currently available relate to reproductive issues rather than hair loss.

What Is the Connection Between Prolactin and FSH? Follicle stimulating hormone (FSH) is directly impacted by prolactin in breastfeeding mothers. The release of prolactin prevents the release and production of FSH. This delays ovulation in many women who breastfeed exclusively during the early months of their infants' lives. A decline in FSH production has the opposite effect, and most women resume normal ovulation and menstruation once the breastfeeding relationship has ended. Prolactin is a hormone produced by a woman's body soon after giving birth. It signals the breasts to make milk, and levels shift upward and downward throughout the day thanks to the brain's “supply and demand” system for breastfeeding. The more the baby nurses, the more milk a mother's body will produce in response, and more the prolactin her body makes in order to keep up with this demand. As prolactin levels increase, FSH decreases. This correlation between prolactin and FSH acts as a natural birth control for women. Follicle stimulating hormone is the chemical which promotes maturation of follicles and eggs within the ovaries each month. By suppressing FSH production, prolactin prevents maturation of an egg and thereby, delays ovulation. Without ovulation a new pregnancy cannot occur. Although the release of prolactin and FSH reduction does prevent ovulation for many, any dip in breastfeeding may throw this off balance. Additionally, prolactin levels may vary from woman to woman, and levels ebb and flow throughout the breastfeeding relationship. As an infant begins eating solid foods, typically between the fourth and sixth months of life, prolactin levels typically begin to decrease in production. This can lead to ovulation at any time thereafter. Because of this, couples should not rely on breastfeeding alone for birth control and should continue to use a backup method. The exact impact of prolactin and FSH on a woman's body may vary with the individual. Some women are not able to produce enough prolactin on their own and medication may be required in order to achieve exclusive breastfeeding. There are also natural methods for increasing prolactin. Fluctuating levels of either hormone may lead a woman to have a period, followed by several months of irregular cycles as hormone levels stabilize. Those who choose not to breastfeed will still produce prolactin for a limited amount of time as the milk “comes in" and then sometimes for several weeks or months after. These women typically have a normal period within a few months of giving birth, and if breastfeeding is not resumed, cycles should regulate within the first year. Women may have a cycle which is slightly different than what they experienced before giving birth. They may be longer or shorter, and periods may be heavier or lighter in nature. Rarely, a woman may have an imbalance of prolactin and FSH. These women may continue producing elevated levels of prolactin even after breastfeeding has decreased or ceased altogether. Ovulation may be delayed in these women, and hormonal supplements may be needed to aid the body in regulating itself. This condition is relatively rare.

What Are the Different Types of FSH Treatment? Follicle-stimulating hormone (FSH) is a substance made by the pituitary gland that stimulates the ovarian follicles in women to release at least one egg every month for ovulation. When FSH levels are too low or too high, the follicles may not be properly stimulated, making reproduction difficult or even impossible without medical intervention. The main type of FSH treatment available is the injection of hormones into the body, which is often called hormone replacement therapy (HRT). Some patients may prefer to try an alternative method of using herbs and nutritious foods to balance out the hormones. Other FSH treatment options may include attaining a healthy weight, reducing stress, and using exercise or acupuncture to improve blood flow to the pelvis. One of the most common types of FSH treatment administered by a doctor is the injection of hormones. For example, those who have low levels of this hormone may have artificial FSH injected into their body in an effort to increase the levels. Patients with low FSH levels may be offered birth control pills or HRT to increase the amount of estrogen and progesterone in the body, which may in turn help produce the right amount of FSH. While these types of FSH treatment may stabilize the levels of this hormone, they do not necessarily increase fertility, because they cannot necessarily improve the quality of the eggs. Such treatment, however, can usually relieve the symptoms that come with high or low FSH. Some treatment options, such as taking herbal supplements and eating certain foods, are considered by some to be more natural than injecting hormones into the body and, because eating the right foods can improve nutrition, such treatment also may improve overall health. For example, bee pollen, spirulina and sea vegetables that include kelp are all known for being nutritious and helping the endocrine system. Including such foods in one's diet, therefore, may result in the pituitary gland secreting the right amount of FSH. Some herbs are said to have similar effects, including maca, vitex and American ginseng. Patients are encouraged to ask their doctor before starting such an FSH treatment, to ensure that it doesn't interfere with any other treatment efforts or health conditions. Patients also may be advised to make a few lifestyle changes in an attempt to stabilize FSH levels. Staying at a healthy weight and keeping stress at bay are a few ways to change FSH levels for the better, because these factors tend to affect hormones. Another alternative option is to try acupuncture in an attempt to increase the blood supply to the ovaries, which may help improve follicle growth and egg production. Yoga or other regular exercise may have a similar effect.

What Are the Effects of Low FSH? Follicle-stimulating hormone, more commonly referred to as FSH, is a hormone which is both produced and released into the body by the pituitary gland. Located in the base of the brain, the pituitary gland is primarily responsible for producing and secreting various hormones which control growth and sexual development. FSH is related to sexual development and functioning in both men and women; therefore, low FSH levels may result in a variety of reproductive conditions. FSH levels may be affected as a result of issues ranging from stress and being underweight to tumors or other abnormalities that prevent the pituitary gland from functioning properly. One of the most common effects of low FSH levels in the body is decreased levels of reproductive cells, which may contribute to infertility if left untreated. In women, this may result in decreased amounts of eggs that are produced by the ovaries. Men who do not have adequate amounts of FSH will generally have a reduced sperm count. Abnormally low amounts of FSH hormones in the body may also affect the physical development of reproductive organs, a condition known as hypogonadism. In males, one of the primary functions of the hormone is to stimulate the growth of the testicles. If an insufficient amount of FSH is present in the body during puberty, it may result in a male having underdeveloped testicles along with decreased functioning of the sperm. Hypogonadism may also occur after puberty and cause loss of body and facial hair, breast growth, muscle loss, and difficulty with sexual functioning. Females who have low amounts of the FSH hormone during puberty may not begin menstruating or developing breasts. If the condition occurs after puberty, a woman may notice a loss in body hair and a decreased level of sexual interest. Low FSH levels in adulthood also tend to result in a stop in menstrual periods. If female hypogonadism is left untreated, it may lead to early menopause. If a person is experiencing issues with sexual development or functioning, a blood sample is usually taken and tested to determine if there are abnormal amounts of the FSH hormone in the body. To prevent permanent complications from low FSH levels, a doctor will typically recommend a patient take a synthetic version of the hormone to help regulate it to a normal level. Inadequate amounts of the hormone may also be one of the symptoms of conditions, such as polycystic ovary disease, Klinefelter syndrome, Turner syndrome, or anorexia. Testing for FSH is often used as a tool to diagnose these conditions and determine the best treatment options.

What Factors Affect FSH Levels? Follicle stimulating hormone (FSH) levels fluctuate due to various health related factors. In women, menopause or ovarian failure will most likely cause an increase in luteinizing hormone (LH) and FSH levels. Primary testicular failure or developmental defects in men can cause an increase of FSH. Low levels of FSH can be attributed to pituitary or hypothalamic issues in both men and women. Women with normally induced perimenopause or menopause are likely to have elevated levels of FSH; however, high amounts of FSH in younger women can signal an abnormal reproductive condition. Increased levels of FSH in non-menopausal women often indicate primary ovarian failure. Failure of the ovaries can be due to development defects, certain cancer treatments and chronic diseases. Developmental defects that lead to an increase of FSH levels in women are ovarian agenesis, Turner’s syndrome and 17 alpha-hydroxylase deficiency. Ovarian agenesis is the developmental failure or absence of one or both ovaries. Turner’s syndrome is a chromosomal abnormality that can potentially cause ovarian agenesis. A condition called 17 alpha-hydroxylase deficiency causes a defect in the ovaries that results in abnormal production of steroid hormones. Similar to women, men with developmental defects are likely to show high levels of FSH. Gonadal agenesis and chromosomal abnormalities are two types of developmental conditions that can be responsible for testicular failure and consequently elevated FSH levels. Gonadal agenesis is the absence or a failure to develop gonads. Klinefelter's syndrome is a chromosomal defect that is characterized by male hypogonadism; a high level of FSH is also indicative of primary hypogonadism. Cancer treatments such as radiation and chemotherapy can interfere with reproductive functions in both men and women. Women may experience ovarian failure, while men will most likely experience testicular failure. For some, reproductive failure is reversible with the cessation of radiation and chemotherapy. Chronic conditions such as autoimmune disorders, adrenal disease and polycystic ovary syndrome (PCOS) can also contribute to high FSH levels. In both sexes, a pituitary tumor can cause low levels of FSH and LH. In addition to low FSH and LH, men will also have low testosterone levels. Consequently, men with low testosterone will suffer from low sex drive and the inability to produce sperm. Women who have prolactin-producing tumors will cease to ovulate and menstruate. Along with low FSH and LH levels, overall estrogen will drop. Pituitary tumors have different growth patterns and affect people in different ways. In some people FSH levels are high while in others the levels may only be slightly elevated.

What Is Serum FSH? Follicle stimulating hormone (FSH) is a hormone made by the pituitary gland that plays a critical role in reproduction. The levels of this hormone vary throughout a person's life. Checking the serum FSH level can yield important information about the function of the ovaries, testes, pituitary gland, and hypothalamus. High levels could suggest menopause, ovarian failure, or testicular failure. Low levels might imply pregnancy or problems with the hypothalamus or pituitary glands. The hormone FSH is made by the anterior pituitary gland, an endocrine gland located in the brain. It is a secreted in response to elevated levels of gonadotropin-releasing hormone (GnRH), manufactured by the hypothalamic region of the brain. Levels of FSH are regulated by a negative-feedback loop. In other words, having high serum levels normally shuts down further production of this hormone. Follicle stimulating hormone is classified as a gonadotroph, which means that it helps to promote the growth and development of the gonads, a general term used to refer to the ovaries or the testes. In men, FSH promotes the growth of the testes, and helps produce a variety of molecules important for the proper growth and development of the sperm. The hormone has a different function in women, as it helps regulate the menstrual cycle and promotes the development of mature eggs. The level of serum FSH, or the concentration of FSH in the blood, varies throughout a person's life. Typically levels are low or undetectable in puberty, and then rise after the onset of reproductive maturity. In women, the level fluctuates throughout the menstrual cycle, being high during the first half of the cycle and lower in the second half. After menopause, levels are typically elevated. Checking the serum FSH is done for a number of reasons, and this hormone tends to be evaluated along with other reproductive hormones, including luteinizing hormone (LH), testosterone, and estrogen. Due to its important role in fertility and reproduction, its levels are often checked in the workup of an infertile couple. Sometimes the serum FSH level is checked in patients with early or late puberty. Additionally, knowing the amount of FSH in the blood could be useful in diagnosing whether a woman has reached menopause. It can also yield important information about women who have ceased having menstrual cycles, a condition known as amenorrhea. High serum FSH levels can signify a number of different conditions. It might suggest the presence of either ovarian or testicular failure. Women who are post-menopausal typically have high levels of this hormone. A number of different illicit drugs can also cause high serum FSH. Low serum FSH levels can also suggest a variety of diseases. Patients who have problems with either their hypothalamus or pituitary glands typically have low levels. Women who are pregnant also usually have low amounts of FSH in their bloodstreams. A number of medications, including corticosteroids and oral contraceptives, can suppress production of this hormone.Follicle-Stimulating Hormone Test A follicle-stimulating hormone test measures the amount of follicle-stimulating hormone (FSH) in a blood sample. FSH is produced by the pituitary gland.

In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. The amount of FSH varies throughout a woman's menstrual cycle and is highest just before she releases an egg (ovulates).

In men, FSH helps control the production of sperm. The amount of FSH in men normally remains constant.

The amounts of FSH and other hormones (luteinizing hormone, estrogen, and progesterone) are measured in both a man and a woman to determine why the couple can't become pregnant (infertility). The FSH level can help determine whether male or female sex organs (testicles or ovaries) are functioning properly.

Description FSH is a glycoprotein gonadotropin secreted by the anterior pituitary in response to gonadotropin-releasing hormone (GnRH), which is released by the hypothalamus. The same pituitary cells also secrete LH, another gonadotropin. An image depicting FSH can be seen below.

FSH and LH are composed of alpha and beta subunits. The specific beta subunit confers the unique biologic activity. FSH and LH bind to receptors in the testis and ovary and regulate gonadal function by promoting sex steroid production and gametogenesis. Both are essential for reproduction in males and females. FSH and LH play central roles in the hypothalamic-pituitary-gonadal axis, and, thus, conditions related to LH and FSH abnormalities can be caused by pathology of either the hypothalamus or pituitary. The two are frequently measured together, along with other hormones. Careful analysis of the presenting problem, the patient’s overall health, and the hormonal profile is often necessary to determine the cause of FSH abnormality and, thus, the most appropriate treatment.Reference Range The reference range for follicle-stimulating hormone (FSH) is as follows:Males Prepubertal: 0-5.0 mIU/mL Pubertal: 0.3-10.0 mIU/mL Adult: 1.5-12.4 mIU/mLFemales Prepubertal: 0-4.0 mIU/mL Pubertal: 0.3-10.0 mIU/mL Premenopausal: Follicular - 1.0-8.8 mIU/dL. Mid-cycle - 4.0-25.0 mIU/mL. Luteal - 1.0-5.1 mIU/mL Postmenopausal: 16.7-134.8 mIU/mL

Indications/Applications Indications for testing of FSH include the following:

Evaluating menstrual irregularities (including anovulatory bleeding)

Evaluating suspected hypogonadism

Evaluating precocious puberty

Predicting ovulation

Evaluating infertility

Evaluating pituitary disorders

Why It Is Done A follicle-stimulating hormone (FSH) test may be done to:

Help find the cause of infertility. FSH testing is commonly used to help evaluate a:

Woman's egg supply (ovarian reserve).

Man's low sperm count.

Help evaluate menstrual problems, such as irregular or absent menstrual periods (amenorrhea). This can help determine whether the woman has gone through menopause.

Determine if a child is going through early puberty (also called precocious puberty). Puberty is early when it starts in girls younger than age 9 and in boys younger than age 10.

Determine why sexual features or organs are not developing when they should (delayed puberty).

Help diagnose certain pituitary gland disorders, such as a tumor.

Collection and Panels Specifics for collection and panels are as follows:

Specimen type: Blood serum

Container: Vacutainer, red/black top

Collection method: Venipuncture

Specimen volume: 0.6 mL

Related tests are as follows:

Total estrogens

Estradiol

Luteinizing hormone (LH)

Testosterone

Progesterone

How to Prepare Many medicines, such as cimetidine, clomiphene, digitalis, and levodopa, can change your test results. You may be asked to stop taking medicines (including birth control pills) that contain estrogen or progesterone or both for up to 4 weeks before having a follicle-stimulating hormone (FSH) test. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you are taking, including herbs and natural substances. Tell your doctor if you have had a test that used a radioactive substance (tracer) within the last 7 days. Recent tests using a radioactive tracer (such as a thyroid scan or bone scan) can interfere with FSH test results. Let your doctor know the first day of your last menstrual period. If your bleeding pattern is light or begins with spotting, the first day is the day of heaviest bleeding. Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form.

How It Is Done The health professional drawing your blood will:

Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.

Clean the needle site with alcohol.

Put the needle into the vein. More than one needle stick may be needed.

Attach a tube to the needle to fill it with blood.

Remove the band from your arm when enough blood is collected.

Apply a gauze pad or cotton ball over the needle site as the needle is removed.

Apply pressure to the site and then a bandage.

For a woman who is having problems with her menstrual cycle or who cannot become pregnant, more than one blood sample may be needed to help identify a follicle-stimulating hormone (FSH) problem. A sample may be taken each day for several days in a row.How It Feels You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. But many people do not feel any pain or have only minor discomfort once the needle is positioned in the vein.

Risks There is very little risk of complications from having blood drawn from a vein.

You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.

In rare cases, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated with a warm compress applied several times daily.

Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood is drawn.

Results A follicle-stimulating hormone test measures the amount of follicle-stimulating hormone (FSH) in a blood sample. The test results depend on your age and stage of sexual development. The phase of a woman's menstrual cycle can affect results, so it is important to know the first day of your last menstrual period at the time the test is performed. Results are usually available within 24 hours.Normal The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.Follicle-stimulating hormone (FSH)

Menstruating women

Follicular phase:

1.37-9.9 international units per liter (IU/L)

Midcycle peak:

6.17-17.2 IU/L

Luteal phase:

1.09-9.2 IU/L

Women past menopause:

19.3-100.6 IU/L

Men:

1.42-15.4 IU/L

Many conditions can change FSH levels. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.High values High FSH values in a woman may mean:

Loss of ovarian function before age 40 (ovarian failure).

Menopause has occurred.

High FSH values in a man may mean:

Klinefelter syndrome.

Testicles are absent or not functioning properly.

Testicles have been damaged by a disease, such as alcohol dependence, or by treatments, such as X-rays or chemotherapy.

High values in children may mean that puberty is about to start.Low values Low FSH values may mean:

A woman is not producing eggs (prevents ovulation) or a man is not producing sperm.

An area of the brain (the hypothalamus or pituitary gland) is not functioning properly.

A tumor is present that interferes with the brain's ability to control FSH production.

Stress.

Starvation or being very underweight.

What Affects the Test Results of the follicle-stimulating hormone (FSH) test may be affected by:

The use of hormones, such as testosterone, estrogen, and progesterone (including birth control pills).

Heavy cigarette smoking.

Age.

The use of medicines, such as cimetidine, clomiphene, digitalis, and levodopa. Make sure your doctor has a complete list of all the prescription and over-the-counter medicines you are taking, including herbs and natural substances.

Having a test such as a thyroid scan or bone scan that uses a radioactive substance within 1 week of the FSH test.

What to Think About If you are taking a medicine that contains testosterone, estrogen, or progesterone (such as birth control pills), ask your doctor whether you should stop taking it for several days before having a follicle-stimulating hormone (FSH) test.